There are 6 interrelated aspects of this project, a project whose main purpose is to determine how microtubules function. We will study 1) the interaction of detergents with hydrophobic regions of various tubulin subunits to better understand protein-protein interactions in microtubules of varied function. We will determine the interactions between the ATPase dynein (and related proteins) with 2) "particulate" tubulin in the cytoplasm and with 3) formed microtubules in vitro, using physical and enzymatic techniques. We will 4) isolate and characterize "component-20", an elusive polypeptide chain which appears to co-polymerize with ciliary microtubules in a length-determining fashion. We will 5) attempt to identify the unique hydrophobic regions of membrane tubulin by selective cleavage of conserved regions from the 2 polypeptide chains. Finally, we will 6) utilize iontophoretic injection of vanadate anion in an effort to locally inhibit chromosome movement, thus testing the possible involvement of dynein-microtubule interaction in mitosis.